scholarly journals Numerical simulation of wind field and sand flux in crescentic sand dunes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huiwen Zhang ◽  
Zhen Wu ◽  
Jing Hu ◽  
Zhiping Zhang ◽  
Bin Xiao ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Wind Field ◽  
Sand Dune ◽  
Eddy Currents ◽  
Sand Dunes ◽  
Turbulent Intensity ◽  
Leeward Side ◽  
Wind Flow ◽  
Simulation Results ◽  
Sand Flux

AbstractSand flux is the key factor to determine the migration of sand dunes and the erosion to the surrounding environment. There are crescent-shaped sand dunes of various scales in the desert, and there are significant differences in spatial wind field and sand flux among them. However, due to the difficulty of monitoring, it is difficult to continuously observe the spatial wind field and sand flux around the larger crescentic dunes. On the basis of the Reynolds-Average Navier–Stokes (RA-NS) equation and the stress and sand flux model, the distribution of wind field and sand flux of a circular dune with a height of 4.2 m and a length of about 100 m during the four evolutionary periods of the evolution into a crescentic dune was simulated in this study. By comparing with the measured results, we verified that the closer to the leeward side, the more the simulated values of the velocity in wind field and sand flux were in line with the measured results. In order to further analyze the influence of the height of dune and other relevant parameters on sand flux, we simulated the influence on wind field and sand flux by changing the air viscosity and wind velocity of upper boundary. We found that the air viscosity mainly affected the amount of deposited sand on the leeward side of sand dune, while the increase of wind velocity would undoubtedly increase the sand flux of the whole sand dune. In addition, the simulation results also showed that the influence of changes in height of dune on the turbulent intensity of leeward side was very significant, and the turbulent intensity increased with the height of dune. The height changes of tall dunes gradually affected the transport of sand caused by wind flow behind the leeward side because that the rotation of the wind flow would form new vortexes at the large pores behind the leeward side, which would increase the turbulent energy in space and thus would increase the distance of migration of the lifting sand. While the low sand dunes could not form extra small vortexes at the bottom of the leeward side, so the wind velocity was small and the eddy currents behind the leeward side were more stable. The simulation results indicated that wind velocity was not the only reason for increasing the amount of sand flux, and the fluctuation of wind flow caused by turbulence could also stimulate the movement of sand particles on the ground.

scholarly journals The Sources of Moisture in the Sand Dunes – The Example of the Western Sahara Dune Field

2014 ◽  
Vol 33 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Elwira Żmudzka ◽  
Dariusz Woronko ◽  
Maciej Dłużewski
Keyword(s):  
Surface Layer ◽  
Moisture Content ◽  
Wind Velocity ◽  
Sand Dune ◽  
Sand Dunes ◽  
Shear Velocity ◽  
Meteorological Conditions ◽  
Aeolian Transport ◽  
Western Sahara ◽  
Dune Field

Abstract Climatic and meteorological conditions may limit the aeolian transport within barchans. An explanation of that issue was the main goal of the investigation held in Western Sahara dune fields located around Tarfaya and Laâyoune. Particular attention was paid to the factors causing the moisture content rising of the sand dune surface layer, which could influence the wind threshold shear velocity in the aeolian transport. The wetted surface layer of sand, when receiving moisture from precipitation or suspensions, reduces the aeolian transport, even in case of wind velocity above 4-5 m s-1. Fog and dew condensation does not affect the moisture of deeper sand layers, what occurs after rainfall.

scholarly journals Three-Dimensional Wind Field Construction and Wind Turbine Siting in an Urban Environment

Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 137 ◽  
Author(s):  
Mingrui Liu ◽  
Xiuling Wang
Keyword(s):  
Wind Turbine ◽  
Urban Environment ◽  
Wind Field ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Urban Environments ◽  
Urban Region ◽  
Wind Flow ◽  
Simulation Results

Three-dimensional urban wind field construction plays an important role not only in the analysis of pedestrian levels of comfort but also in the effectiveness of harnessing wind energy in an urban environment. However, it is challenging to accurately simulate urban wind flow due to the complex land use in urban environments. In this study, a three-dimensional numerical model was developed for urban wind flow construction. To obtain an accurate urban wind field, various turbulence models, including the Reynolds stress model (RSM), k-ω shear stress transport (SST), realizable k-ε, and (Re-Normalisation Group (RNG) k-ε models were tested. Simulation results were compared with experimental data in the literature. The RSM model showed promising potential in simulating urban wind flow. The model was then adopted to simulate urban wind flow for Purdue University Northwest, which is located in the Northwest Indiana urban region. Based on the simulation results, the optimal location was identified for urban wind turbine siting.

scholarly journals FIELD MEASUREMENT OF AEOLIAN SAND FLUX USING CERAMIC SAND FLUX SENSOR UD-101 AT A SAND DUNE

2011 ◽  
Vol 1 (32) ◽  
pp. 109
Author(s):  
Keiko Udo ◽  
Junaidi Junaidi ◽  
Shin-ichi Aoki ◽  
Shota Mitsushio ◽  
Shigeru Kato ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Sand Dune ◽  
Field Measurements ◽  
Sand Transport ◽  
Aeolian Sand ◽  
Aeolian Sand Transport ◽  
Charnock Constant ◽  
Sand Flux ◽  
Transport Flux ◽  
Flux Sensor

This study conducted field observations in terms of the number of blown sand impacts and wind velocity at an open ocean beach in Japan, in order to investigate characteristics of the aeolian sand transport flux over a sand dune slope. Charnock constant of a roughness length equation calculated from wind velocity data had a larger value over the slope compared to over a flat. Furthermore, the aeolian flux over the slope tended to be larger than that over the flat. Characteristics of the Charnock constant and the aeolian flux over the flat and the slope were demonstrated from the field measurements.

scholarly journals Modeling sand slides by a mechanics-based degenerate parabolic equation

2018 ◽  
Vol 24 (8) ◽  
pp. 2558-2575 ◽  
Author(s):  
A. Lo Giudice ◽  
G. Giammanco ◽  
D. Fransos ◽  
L. Preziosi
Keyword(s):  
Degenerate Parabolic Equation ◽  
Sand Dunes ◽  
Leeward Side ◽  
Kinematic Evolution ◽  
Physically Based ◽  
External Sources ◽  
Degenerate Parabolic ◽  
Simulation Results ◽  
High Flexibility ◽  
Sand Piles

Avalanching plays a crucial role in granular materials dynamics, in particular in the evolution of the shape of the leeward side of sand dunes. This paper presents a physically-based mathematical model capable of reproducing the kinematic evolution of the surface of sand piles and to obtain eventually the stationary configurations, in the presence of external sources as well. Simulation results with different boundary conditions and geometries are reported in order to show the high flexibility of the model. The model is also validated by means of comparison with the experimental results of different authors.

A mesoscale model application to fire weather winds

1999 ◽  
Vol 9 (4) ◽  
pp. 255 ◽  
Author(s):  
José A. Gómez-Tejedor ◽  
María J. Estrela ◽  
Millán M. Millán
Keyword(s):  
Wind Field ◽  
Mediterranean Basin ◽  
Mesoscale Model ◽  
Model Simulation ◽  
Wind Flow ◽  
Fire Weather ◽  
Fire Event ◽  
Important Conclusion ◽  
Model Application ◽  
Simulation Results

In this work, a mesoscale model has been used to simulate the wind flow in a real fire situation in the Spanish Mediterranean basin in July 1991. The model simulation results for the wind field are shown, and compared to the fire evolution, and to some real observations taken in the area during the fire event. The most important conclusion is that, in spite of the presence of the fire, the mesoscale model was still able to predict the local winds accurately without taking the fire heating processes into account.

Integration of Computational Fluids Dynamics and Virtual Reality Visualization for Constructing the Wind Field

2011 ◽  
Author(s):  
Lu Lu ◽  
Xiuling Wang
Keyword(s):  
Virtual Reality ◽  
Statistical Analysis ◽  
Virtual Environment ◽  
Wind Field ◽  
Cfd Simulation ◽  
Wind Flow ◽  
Wind Condition ◽  
Irregular Terrain ◽  
Geometry Model ◽  
Simulation Results

3-D wind field models were developed for constructing 3-D wind fields in an urban wind condition and over irregular terrain. The virtual environment is used to visualize the simulation results. Simulation results based on statistical input data were obtained for 3-D urban wind flow over the Classroom and Office (CLO) building at Purdue University Calumet (PUC). The objective for this project was to construct the 3D wind field around the roof of the CLO building in order to analyze the wind condition and identify a suitable installation area which would have relatively more wind power but less turbulence for the wind turbine. By using the virtual reality (VR) technique, the simulation results can be clearly and vividly shown in a virtual environment that would not be as limited as traditional two-dimensional views. Statistical analysis was based on the wind data that was recorded by a sensor located on the roof of the CLO building. Specific wind conditions, which were obtained from the statistical analysis, were applied to simulation cases for the wind flow around a 3-D geometry model of the CLO building. In addition, different wind directions were applied in the Fluent program. After the CFD simulation results were exported, the virtual reality technique was used to visualize the simulation results, which can be observed intuitively. Visualization of simulation results are easier to be observed and be analyzed.

Seedling desiccation tolerance of Leymus racemosus (Poaceae) (wild rye), a perennial sand-dune grass inhabiting the Junggar Basin of Xinjiang, China

2004 ◽  
Vol 14 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Zhenying Huang ◽  
Yitzchak Gutterman
Keyword(s):  
Desiccation Tolerance ◽  
Sand Dune ◽  
Sand Dunes ◽  
Perennial Grass ◽  
Junggar Basin ◽  
Seedling Development ◽  
Ecological Implications ◽  
Leymus Racemosus ◽  
Seedling Desiccation Tolerance ◽  
Dune Grass

Leymus Racemosus, The Mammoth Wild Rye, Is A Rhizomatous Perennial Grass, Mainly Distributed In The Moving Or Semi-Stabilized Sand Dunes In Deserts Of The Junggar Basin In Xinjiang, China. The Revival Ability Of The Young Seedling After Periods Of Desiccation Can Be Influenced By Several Factors: (1) The Stage Of Seedling Development – The Later The Stage At Dehydration, The Longer The Root Length And The Lower Is The Percentage Of Seedlings That Survive; (2) The Length Of The Period Of Desiccation – The Longer The Period That The Seedlings Are Under Desiccation, The Lower Is The Percentage Of Seedlings That Survive; (3) Endosperm Size – The Smaller The Proportion Of Endosperm That Remains In The Caryopses, The Lower Is The Percentage Of Seedlings That Revive, Determined By (A) The Stage Of Seedling Development, And (B) The Proportion Of The Endosperm That Is Removed By Cutting; And (4) Caryopsis Size – The Larger The Polymorphic Caryopses, The Higher Is The Percentage Of Young Seedlings That Revive From Periods Of Desiccation. The Physiological And Ecological Implications Of L. Racemosus Seedling Desiccation Tolerance Are That Under Extreme Desert And Unpredictable Environmental Conditions, The Chances Of Seedling Establishment Are Increased.

Modelling the wind flow pattern around a parabolic sand dune

1990 ◽  
Vol 32 (1-2) ◽  
pp. 89-94 ◽  
Author(s):  
J.J. Finnigan ◽  
D. Neil ◽  
B.G. Lees ◽  
R.J. Croome ◽  
M. Woodgate
Keyword(s):  
Flow Pattern ◽  
Sand Dune ◽  
Wind Flow

scholarly journals Wind Velocity Decreasing Effects of Windbreak Fence for Snowfall Measurement

2014 ◽  
Vol 2014 ◽  
pp. 1-20
Author(s):  
Ki-Pyo You ◽  
Young-Moon Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Velocity ◽  
Wind Tunnel Test ◽  
Field Measurements ◽  
Wind Flow ◽  
Dynamics Analysis ◽  
Computational Fluid Dynamics Analysis ◽  
Better Than ◽  
Velocity Decrease

Meteorological observatories use measuring boards on even ground in open areas to measure the amount of snowfall. In order to measure the amount of snowfall, areas unaffected by wind should be found. This study tried to determine the internal wind flow inside a windbreak fence, identifying an area unaffected by wind in order to measure the snowfall. We performed a computational fluid dynamics analysis and wind tunnel test, conducted field measurements of the type and height of the windbreak fence, and analyzed the wind flow inside the fence. The results showed that a double windbreak fence was better than a single windbreak fence for decreasing wind velocity. The double fence (width 4 m, height 60 cm, and fixed on the bottom) has the greatest wind velocity decrease rate at the central part of octagonal windbreak.

Allelopathic potential of Artemisia campestris ssp. caudata on Lake Huron sand dunes

1997 ◽  
Vol 75 (11) ◽  
pp. 1903-1912 ◽  
Author(s):  
Kyeong W. Yun ◽  
M. A. Maun
Keyword(s):  
Seed Germination ◽  
Seedling Growth ◽  
Mycorrhizal Fungi ◽  
Sand Dune ◽  
Sand Dunes ◽  
Dry Weight ◽  
Fungal Colonization ◽  
Test Species ◽  
Allelopathic Potential ◽  
Artemisia Campestris

Greenhouse studies were conducted to test allelopathic effects of Artemisia campestris ssp. caudata on seed germination and seedling growth of several sand-dune species and colonization by mycorrhizal fungi. The aqueous extracts of A. campestris showed no inhibitory effect on seed germination, seedling elongation, or dry-weight growth of plants at lower concentrations (10 and 50%), but 100% concentration of the extracts caused varying degrees of inhibition depending on the test species. The mixing of dry leaves of seedlings of A. campestris to the sand showed severe inhibition of Elymus canadensis seedlings. The percent germination of test species in soil from the rhizosphere of A. campestris was significantly lower than that of the control. The leaf area and dry weight were also lower but the differences were not significant. The aqueous extract inhibited mycorrhizal fungal colonization in roots of three sand-dune grasses. Key words: allelopathy, Artemisia campestris ssp. caudata, seed germination, seedling growth, mycorrhizal fungi.

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